VHB-JOURQUAL2: Method, Results, and Implications of the German Academic Association for Business Research's Journal Ranking

VHB-JOURQUAL represents the official journal ranking of the German Academic Association for Business Research. Since its introduction in 2003, the ranking has become the most influential journal evaluation approach in German-speaking countries, impacting several key managerial decisions of German, Austrian, and Swiss business schools. This article reports the methodological approach of the ranking’s second edition. It also presents the main results and additional analyses on the validity of the rating and the underlying decision processes of the respondents. Selected implications for researchers and higher-education institutions are discussed.

Hierarchical segmentation-assisted multimodal registration for MR brain images

Information theory-based metric such as mutual information (MI) is widely used as similarity measurement for multimodal registration. Nevertheless, this metric may lead to matching ambiguity for non-rigid registration. Moreover, maximization of MI alone does not necessarily produce an optimal solution. In this paper, we propose a segmentation-assisted similarity metric based on point-wise mutual information (PMI). This similarity metric, termed SPMI, enhances the registration accuracy by considering tissue classification probabilities as prior information, which is generated from an expectation maximization (EM) algorithm. Diffeomorphic demons is then adopted as the registration model and is optimized in a hierarchical framework (H-SPMI) based on different levels of anatomical structure as prior knowledge. The proposed method is evaluated using Brainweb synthetic data and clinical fMRI images. Both qualitative and quantitative assessment were performed as well as a sensitivity analysis to the segmentation error. Compared to the pure intensity-based approaches which only maximize mutual information, we show that the proposed algorithm provides significantly better accuracy on both synthetic and clinical data.

An Extended Hierarchical Task Analysis for Error Prediction in Medical Devices

This paper introduces an extended hierarchical task analysis (HTA) methodology devised to evaluate and compare user interfaces on volumetric infusion pumps. The pumps were studied along the dimensions of overall usability and propensity for generating human error. With HTA as our framework, we analyzed six pumps on a variety of common tasks using Norman’s Action theory. The introduced method of evaluation divides the problem space between the external world of the device interface and the user’s internal cognitive world, allowing for predictions of potential user errors at the human-device level. In this paper, one detailed analysis is provided as an example, comparing two different pumps on two separate tasks. The results demonstrate the inherent variation, often the cause of usage errors, found with infusion pumps being used in hospitals today. The reported methodology is a useful tool for evaluating human performance and predicting potential user errors with infusion pumps and other simple medical devices.

Body image rating scales to assess obesity

Obesity prevalence in the U.S. has increased during the last three decades with major impact on public health. Screening for obesity in a population with unknown weight status can be time- and resource-consuming, but the information is valuable for prioritizing and allocating scarce resources. The challenge remains to properly assess obesity with the available methods. Body Image Rating Scales (BIRS) have initially been developed to assess body image disturbances, but also seem useful as an alternative method in assessing obesity prevalence. Several different BIRS exists. In this project I reviewed the literature that exists regarding the use of BIRS, and its advantages and limitations for the assessment of obesity status with regards to BMI. The result yielded nine publications that examined eight different scales and their correlation with BMI, ranging from r=.59 for self-reported BMI to r=.94 for measured BMI. One concern is the lack of standardization of this method to assess obesity, given the range of different scales. While many methods for obesity assessment are available, the simplicity, ease of use and cost-effectiveness of BIRS make it very appealing. BIRS remain a potentially attractive option to assess the weight status of a large population with minimal requirements in assets and time, especially in situations where measuring instruments are not available, or when height or weight could not be recalled.^

Robust effect sizes and their confidence intervals for group difference between trajectories in hierarchical linear growth model

Hierarchical linear growth model (HLGM), as a flexible and powerful analytic method, has played an increased important role in psychology, public health and medical sciences in recent decades. Mostly, researchers who conduct HLGM are interested in the treatment effect on individual trajectories, which can be indicated by the cross-level interaction effects. However, the statistical hypothesis test for the effect of cross-level interaction in HLGM only show us whether there is a significant group difference in the average rate of change, rate of acceleration or higher polynomial effect; it fails to convey information about the magnitude of the difference between the group trajectories at specific time point. Thus, reporting and interpreting effect sizes have been increased emphases in HLGM in recent years, due to the limitations and increased criticisms for statistical hypothesis testing. However, most researchers fail to report these model-implied effect sizes for group trajectories comparison and their corresponding confidence intervals in HLGM analysis, since lack of appropriate and standard functions to estimate effect sizes associated with the model-implied difference between grouping trajectories in HLGM, and also lack of computing packages in the popular statistical software to automatically calculate them. ^ The present project is the first to establish the appropriate computing functions to assess the standard difference between grouping trajectories in HLGM. We proposed the two functions to estimate effect sizes on model-based grouping trajectories difference at specific time, we also suggested the robust effect sizes to reduce the bias of estimated effect sizes. Then, we applied the proposed functions to estimate the population effect sizes (d ) and robust effect sizes (du) on the cross-level interaction in HLGM by using the three simulated datasets, and also we compared the three methods of constructing confidence intervals around d and du recommended the best one for application. At the end, we constructed 95% confidence intervals with the suitable method for the effect sizes what we obtained with the three simulated datasets. ^ The effect sizes between grouping trajectories for the three simulated longitudinal datasets indicated that even though the statistical hypothesis test shows no significant difference between grouping trajectories, effect sizes between these grouping trajectories can still be large at some time points. Therefore, effect sizes between grouping trajectories in HLGM analysis provide us additional and meaningful information to assess group effect on individual trajectories. In addition, we also compared the three methods to construct 95% confident intervals around corresponding effect sizes in this project, which handled with the uncertainty of effect sizes to population parameter. We suggested the noncentral t-distribution based method when the assumptions held, and the bootstrap bias-corrected and accelerated method when the assumptions are not met.^

Hierarchical graph maps for visualization of collaborative recommender systems

In this paper we provide a method that allows the visualization of similarity relationships present between items of collaborative filtering recommender systems, as well as the relative importance of each of these. The objective is to offer visual representations of the recommender system?s set of items and of their relationships; these graphs show us where the most representative information can be found and which items are rated in a more similar way by the recommender system?s community of users. The visual representations achieved take the shape of phylogenetic trees, displaying the numerical similarity and the reliability between each pair of items considered to be similar. As a case study we provide the results obtained using the public database Movielens 1M, which contains 3900 movies.

Método experimental para la caracterización de las diferentes tecnologías de integración arquitectónica de la energía fotovoltaica en condiciones de funcionamiento real = Experimental method for characterization of several building integrated photovoltaic technologies under real working conditions

Hoy en día, el proceso de un proyecto sostenible persigue realizar edificios de elevadas prestaciones que son, energéticamente eficientes, saludables y económicamente viables utilizando sabiamente recursos renovables para minimizar el impacto sobre el medio ambiente reduciendo, en lo posible, la demanda de energía, lo que se ha convertido, en la última década, en una prioridad. La Directiva 2002/91/CE "Eficiencia Energética de los Edificios" (y actualizaciones posteriores) ha establecido el marco regulatorio general para el cálculo de los requerimientos energéticos mínimos. Desde esa fecha, el objetivo de cumplir con las nuevas directivas y protocolos ha conducido las políticas energéticas de los distintos países en la misma dirección, centrándose en la necesidad de aumentar la eficiencia energética en los edificios, la adopción de medidas para reducir el consumo, y el fomento de la generación de energía a través de fuentes renovables. Los edificios de energía nula o casi nula (ZEB, Zero Energy Buildings ó NZEB, Net Zero Energy Buildings) deberán convertirse en un estándar de la construcción en Europa y con el fin de equilibrar el consumo de energía, además de reducirlo al mínimo, los edificios necesariamente deberán ser autoproductores de energía. Por esta razón, la envolvente del edifico y en particular las fachadas son importantes para el logro de estos objetivos y la tecnología fotovoltaica puede tener un papel preponderante en este reto. Para promover el uso de la tecnología fotovoltaica, diferentes programas de investigación internacionales fomentan y apoyan soluciones para favorecer la integración completa de éstos sistemas como elementos arquitectónicos y constructivos, los sistemas BIPV (Building Integrated Photovoltaic), sobre todo considerando el próximo futuro hacia edificios NZEB. Se ha constatado en este estudio que todavía hay una falta de información útil disponible sobre los sistemas BIPV, a pesar de que el mercado ofrece una interesante gama de soluciones, en algunos aspectos comparables a los sistemas tradicionales de construcción. Pero por el momento, la falta estandarización y de una regulación armonizada, además de la falta de información en las hojas de datos técnicos (todavía no comparables con las mismas que están disponibles para los materiales de construcción), hacen difícil evaluar adecuadamente la conveniencia y factibilidad de utilizar los componentes BIPV como parte integrante de la envolvente del edificio. Organizaciones internacionales están trabajando para establecer las normas adecuadas y procedimientos de prueba y ensayo para comprobar la seguridad, viabilidad y fiabilidad estos sistemas. Sin embargo, hoy en día, no hay reglas específicas para la evaluación y caracterización completa de un componente fotovoltaico de integración arquitectónica de acuerdo con el Reglamento Europeo de Productos de la Construcción, CPR 305/2011. Los productos BIPV, como elementos de construcción, deben cumplir con diferentes aspectos prácticos como resistencia mecánica y la estabilidad; integridad estructural; seguridad de utilización; protección contra el clima (lluvia, nieve, viento, granizo), el fuego y el ruido, aspectos que se han convertido en requisitos esenciales, en la perspectiva de obtener productos ambientalmente sostenibles, saludables, eficientes energéticamente y económicamente asequibles. Por lo tanto, el módulo / sistema BIPV se convierte en una parte multifuncional del edificio no sólo para ser física y técnicamente "integrado", además de ser una oportunidad innovadora del diseño. Las normas IEC, de uso común en Europa para certificar módulos fotovoltaicos -IEC 61215 e IEC 61646 cualificación de diseño y homologación del tipo para módulos fotovoltaicos de uso terrestre, respectivamente para módulos fotovoltaicos de silicio cristalino y de lámina delgada- atestan únicamente la potencia del módulo fotovoltaico y dan fe de su fiabilidad por un período de tiempo definido, certificando una disminución de potencia dentro de unos límites. Existe también un estándar, en parte en desarrollo, el IEC 61853 (“Ensayos de rendimiento de módulos fotovoltaicos y evaluación energética") cuyo objetivo es la búsqueda de procedimientos y metodologías de prueba apropiados para calcular el rendimiento energético de los módulos fotovoltaicos en diferentes condiciones climáticas. Sin embargo, no existen ensayos normalizados en las condiciones específicas de la instalación (p. ej. sistemas BIPV de fachada). Eso significa que es imposible conocer las efectivas prestaciones de estos sistemas y las condiciones ambientales que se generan en el interior del edificio. La potencia nominal de pico Wp, de un módulo fotovoltaico identifica la máxima potencia eléctrica que éste puede generar bajo condiciones estándares de medida (STC: irradición 1000 W/m2, 25 °C de temperatura del módulo y distribución espectral, AM 1,5) caracterizando eléctricamente el módulo PV en condiciones específicas con el fin de poder comparar los diferentes módulos y tecnologías. El vatio pico (Wp por su abreviatura en inglés) es la medida de la potencia nominal del módulo PV y no es suficiente para evaluar el comportamiento y producción del panel en términos de vatios hora en las diferentes condiciones de operación, y tampoco permite predecir con convicción la eficiencia y el comportamiento energético de un determinado módulo en condiciones ambientales y de instalación reales. Un adecuado elemento de integración arquitectónica de fachada, por ejemplo, debería tener en cuenta propiedades térmicas y de aislamiento, factores como la transparencia para permitir ganancias solares o un buen control solar si es necesario, aspectos vinculados y dependientes en gran medida de las condiciones climáticas y del nivel de confort requerido en el edificio, lo que implica una necesidad de adaptación a cada contexto específico para obtener el mejor resultado. Sin embargo, la influencia en condiciones reales de operación de las diferentes soluciones fotovoltaicas de integración, en el consumo de energía del edificio no es fácil de evaluar. Los aspectos térmicos del interior del ambiente o de iluminación, al utilizar módulos BIPV semitransparentes por ejemplo, son aún desconocidos. Como se dijo antes, la utilización de componentes de integración arquitectónica fotovoltaicos y el uso de energía renovable ya es un hecho para producir energía limpia, pero también sería importante conocer su posible contribución para mejorar el confort y la salud de los ocupantes del edificio. Aspectos como el confort, la protección o transmisión de luz natural, el aislamiento térmico, el consumo energético o la generación de energía son aspectos que suelen considerarse independientemente, mientras que todos juntos contribuyen, sin embargo, al balance energético global del edificio. Además, la necesidad de dar prioridad a una orientación determinada del edificio, para alcanzar el mayor beneficio de la producción de energía eléctrica o térmica, en el caso de sistemas activos y pasivos, respectivamente, podría hacer estos últimos incompatibles, pero no necesariamente. Se necesita un enfoque holístico que permita arquitectos e ingenieros implementar sistemas tecnológicos que trabajen en sinergia. Se ha planteado por ello un nuevo concepto: "C-BIPV, elemento fotovoltaico consciente integrado", esto significa necesariamente conocer los efectos positivos o negativos (en términos de confort y de energía) en condiciones reales de funcionamiento e instalación. Propósito de la tesis, método y resultados Los sistemas fotovoltaicos integrados en fachada son a menudo soluciones de vidrio fácilmente integrables, ya que por lo general están hechos a medida. Estos componentes BIPV semitransparentes, integrados en el cerramiento proporcionan iluminación natural y también sombra, lo que evita el sobrecalentamiento en los momentos de excesivo calor, aunque como componente estático, asimismo evitan las posibles contribuciones pasivas de ganancias solares en los meses fríos. Además, la temperatura del módulo varía considerablemente en ciertas circunstancias influenciada por la tecnología fotovoltaica instalada, la radiación solar, el sistema de montaje, la tipología de instalación, falta de ventilación, etc. Este factor, puede suponer un aumento adicional de la carga térmica en el edificio, altamente variable y difícil de cuantificar. Se necesitan, en relación con esto, más conocimientos sobre el confort ambiental interior en los edificios que utilizan tecnologías fotovoltaicas integradas, para abrir de ese modo, una nueva perspectiva de la investigación. Con este fin, se ha diseñado, proyectado y construido una instalación de pruebas al aire libre, el BIPV Env-lab "BIPV Test Laboratory", para la caracterización integral de los diferentes módulos semitransparentes BIPV. Se han definido también el método y el protocolo de ensayos de caracterización en el contexto de un edificio y en condiciones climáticas y de funcionamiento reales. Esto ha sido posible una vez evaluado el estado de la técnica y la investigación, los aspectos que influyen en la integración arquitectónica y los diferentes tipos de integración, después de haber examinado los métodos de ensayo para los componentes de construcción y fotovoltaicos, en condiciones de operación utilizadas hasta ahora. El laboratorio de pruebas experimentales, que consiste en dos habitaciones idénticas a escala real, 1:1, ha sido equipado con sensores y todos los sistemas de monitorización gracias a los cuales es posible obtener datos fiables para evaluar las prestaciones térmicas, de iluminación y el rendimiento eléctrico de los módulos fotovoltaicos. Este laboratorio permite el estudio de tres diferentes aspectos que influencian el confort y consumo de energía del edificio: el confort térmico, lumínico, y el rendimiento energético global (demanda/producción de energía) de los módulos BIPV. Conociendo el balance de energía para cada tecnología solar fotovoltaica experimentada, es posible determinar cuál funciona mejor en cada caso específico. Se ha propuesto una metodología teórica para la evaluación de estos parámetros, definidos en esta tesis como índices o indicadores que consideran cuestiones relacionados con el bienestar, la energía y el rendimiento energético global de los componentes BIPV. Esta metodología considera y tiene en cuenta las normas reglamentarias y estándares existentes para cada aspecto, relacionándolos entre sí. Diferentes módulos BIPV de doble vidrio aislante, semitransparentes, representativos de diferentes tecnologías fotovoltaicas (tecnología de silicio monocristalino, m-Si; de capa fina en silicio amorfo unión simple, a-Si y de capa fina en diseleniuro de cobre e indio, CIS) fueron seleccionados para llevar a cabo una serie de pruebas experimentales al objeto de demostrar la validez del método de caracterización propuesto. Como resultado final, se ha desarrollado y generado el Diagrama Caracterización Integral DCI, un sistema gráfico y visual para representar los resultados y gestionar la información, una herramienta operativa útil para la toma de decisiones con respecto a las instalaciones fotovoltaicas. Este diagrama muestra todos los conceptos y parámetros estudiados en relación con los demás y ofrece visualmente toda la información cualitativa y cuantitativa sobre la eficiencia energética de los componentes BIPV, por caracterizarlos de manera integral. ABSTRACT A sustainable design process today is intended to produce high-performance buildings that are energy-efficient, healthy and economically feasible, by wisely using renewable resources to minimize the impact on the environment and to reduce, as much as possible, the energy demand. In the last decade, the reduction of energy needs in buildings has become a top priority. The Directive 2002/91/EC “Energy Performance of Buildings” (and its subsequent updates) established a general regulatory framework’s methodology for calculation of minimum energy requirements. Since then, the aim of fulfilling new directives and protocols has led the energy policies in several countries in a similar direction that is, focusing on the need of increasing energy efficiency in buildings, taking measures to reduce energy consumption, and fostering the use of renewable sources. Zero Energy Buildings or Net Zero Energy Buildings will become a standard in the European building industry and in order to balance energy consumption, buildings, in addition to reduce the end-use consumption should necessarily become selfenergy producers. For this reason, the façade system plays an important role for achieving these energy and environmental goals and Photovoltaic can play a leading role in this challenge. To promote the use of photovoltaic technology in buildings, international research programs encourage and support solutions, which favors the complete integration of photovoltaic devices as an architectural element, the so-called BIPV (Building Integrated Photovoltaic), furthermore facing to next future towards net-zero energy buildings. Therefore, the BIPV module/system becomes a multifunctional building layer, not only physically and functionally “integrated” in the building, but also used as an innovative chance for the building envelope design. It has been found in this study that there is still a lack of useful information about BIPV for architects and designers even though the market is providing more and more interesting solutions, sometimes comparable to the existing traditional building systems. However at the moment, the lack of an harmonized regulation and standardization besides to the non-accuracy in the technical BIPV datasheets (not yet comparable with the same ones available for building materials), makes difficult for a designer to properly evaluate the fesibility of this BIPV components when used as a technological system of the building skin. International organizations are working to establish the most suitable standards and test procedures to check the safety, feasibility and reliability of BIPV systems. Anyway, nowadays, there are no specific rules for a complete characterization and evaluation of a BIPV component according to the European Construction Product Regulation, CPR 305/2011. BIPV products, as building components, must comply with different practical aspects such as mechanical resistance and stability; structural integrity; safety in use; protection against weather (rain, snow, wind, hail); fire and noise: aspects that have become essential requirements in the perspective of more and more environmentally sustainable, healthy, energy efficient and economically affordable products. IEC standards, commonly used in Europe to certify PV modules (IEC 61215 and IEC 61646 respectively crystalline and thin-film ‘Terrestrial PV Modules-Design Qualification and Type Approval’), attest the feasibility and reliability of PV modules for a defined period of time with a limited power decrease. There is also a standard (IEC 61853, ‘Performance Testing and Energy Rating of Terrestrial PV Modules’) still under preparation, whose aim is finding appropriate test procedures and methodologies to calculate the energy yield of PV modules under different climate conditions. Furthermore, the lack of tests in specific conditions of installation (e.g. façade BIPV devices) means that it is difficult knowing the exact effective performance of these systems and the environmental conditions in which the building will operate. The nominal PV power at Standard Test Conditions, STC (1.000 W/m2, 25 °C temperature and AM 1.5) is usually measured in indoor laboratories, and it characterizes the PV module at specific conditions in order to be able to compare different modules and technologies on a first step. The “Watt-peak” is not enough to evaluate the panel performance in terms of Watt-hours of various modules under different operating conditions, and it gives no assurance of being able to predict the energy performance of a certain module at given environmental conditions. A proper BIPV element for façade should take into account thermal and insulation properties, factors as transparency to allow solar gains if possible or a good solar control if necessary, aspects that are linked and high dependent on climate conditions and on the level of comfort to be reached. However, the influence of different façade integrated photovoltaic solutions on the building energy consumption is not easy to assess under real operating conditions. Thermal aspects, indoor temperatures or luminance level that can be expected using building integrated PV (BIPV) modules are not well known. As said before, integrated photovoltaic BIPV components and the use of renewable energy is already a standard for green energy production, but would also be important to know the possible contribution to improve the comfort and health of building occupants. Comfort, light transmission or protection, thermal insulation or thermal/electricity power production are aspects that are usually considered alone, while all together contribute to the building global energy balance. Besides, the need to prioritize a particular building envelope orientation to harvest the most benefit from the electrical or thermal energy production, in the case of active and passive systems respectively might be not compatible, but also not necessary. A holistic approach is needed to enable architects and engineers implementing technological systems working in synergy. A new concept have been suggested: “C-BIPV, conscious integrated BIPV”. BIPV systems have to be “consciously integrated” which means that it is essential to know the positive and negative effects in terms of comfort and energy under real operating conditions. Purpose of the work, method and results The façade-integrated photovoltaic systems are often glass solutions easily integrable, as they usually are custommade. These BIPV semi-transparent components integrated as a window element provides natural lighting and shade that prevents overheating at times of excessive heat, but as static component, likewise avoid the possible solar gains contributions in the cold months. In addition, the temperature of the module varies considerably in certain circumstances influenced by the PV technology installed, solar radiation, mounting system, lack of ventilation, etc. This factor may result in additional heat input in the building highly variable and difficult to quantify. In addition, further insights into the indoor environmental comfort in buildings using integrated photovoltaic technologies are needed to open up thereby, a new research perspective. This research aims to study their behaviour through a series of experiments in order to define the real influence on comfort aspects and on global energy building consumption, as well as, electrical and thermal characteristics of these devices. The final objective was to analyze a whole set of issues that influence the global energy consumption/production in a building using BIPV modules by quantifying the global energy balance and the BIPV system real performances. Other qualitative issues to be studied were comfort aspect (thermal and lighting aspects) and the electrical behaviour of different BIPV technologies for vertical integration, aspects that influence both energy consumption and electricity production. Thus, it will be possible to obtain a comprehensive global characterization of BIPV systems. A specific design of an outdoor test facility, the BIPV Env-lab “BIPV Test Laboratory”, for the integral characterization of different BIPV semi-transparent modules was developed and built. The method and test protocol for the BIPV characterization was also defined in a real building context and weather conditions. This has been possible once assessed the state of the art and research, the aspects that influence the architectural integration and the different possibilities and types of integration for PV and after having examined the test methods for building and photovoltaic components, under operation conditions heretofore used. The test laboratory that consists in two equivalent test rooms (1:1) has a monitoring system in which reliable data of thermal, daylighting and electrical performances can be obtained for the evaluation of PV modules. The experimental set-up facility (testing room) allows studying three different aspects that affect building energy consumption and comfort issues: the thermal indoor comfort, the lighting comfort and the energy performance of BIPV modules tested under real environmental conditions. Knowing the energy balance for each experimented solar technology, it is possible to determine which one performs best. A theoretical methodology has been proposed for evaluating these parameters, as defined in this thesis as indices or indicators, which regard comfort issues, energy and the overall performance of BIPV components. This methodology considers the existing regulatory standards for each aspect, relating them to one another. A set of insulated glass BIPV modules see-through and light-through, representative of different PV technologies (mono-crystalline silicon technology, mc-Si, amorphous silicon thin film single junction, a-Si and copper indium selenide thin film technology CIS) were selected for a series of experimental tests in order to demonstrate the validity of the proposed characterization method. As result, it has been developed and generated the ICD Integral Characterization Diagram, a graphic and visual system to represent the results and manage information, a useful operational tool for decision-making regarding to photovoltaic installations. This diagram shows all concepts and parameters studied in relation to each other and visually provides access to all the results obtained during the experimental phase to make available all the qualitative and quantitative information on the energy performance of the BIPV components by characterizing them in a comprehensive way.

Beta diversity at multiple hierarchical levels: explaining the high diversity of scarab beetles in tropical montane forests

Aim: High gamma diversity in tropical montane forests may be ascribed to high geographical turnover of community composition, resulting from population isolation that leads to speciation. We studied the evolutionary processes responsible for diversity and turnover in assemblages of tropical scarab beetles (Scarabaeidae) by assessing DNA sequence variation at multiple hierarchical levels. Location: A 300-km transect across six montane forests (900–1100 m) in Costa Rica. Methods: Assemblages of Scarabaeidae (subfamilies Dynastinae, Rutelinae, Melolonthinae) including 118 morphospecies and > 500 individuals were sequenced for the cox1 gene to establish species limits with a mixed Yule–coalescent method. A species-level phylogenetic tree was constructed from cox1 and rrnL genes. Total diversity and turnover among assemblages were then assessed at three hierarchical levels: haplotypes, species and higher clades. Results: DNA-based analyses showed high turnover among communities at all hierarchical levels. Turnover was highest at the haplotype level (community similarity 0.02–0.12) and decreased with each step of the hierarchy (species: 0.21–0.46; clades: 0.41–0.43). Both compositional and phylogenetic similarities of communities were geographically structured, but turnover was not correlated with distance among forests. When three major clades were investigated separately, communities of Dynastinae showed consistently higher alpha diversity, larger species ranges and lower turnover than Rutelinae and Melolonthinae. Main conclusions: Scarab communities of montane forests show evidence of evolutionary persistence of communities in relative isolation, presumably tracking suitable habitats elevationally to accommodate climatic changes. Patterns of diversity on all hierarchical levels seem to be determined by restricted dispersal, and differences in Dynastinae could be explained by their greater dispersal ability. Community-wide DNA sequencing across multiple lineages and hierarchical levels reveals the evolutionary processes that led to high beta diversity in tropical montane forests through time.

Feature selection by multi-objective optimisation: Application to network anomaly detection by hierarchical self-organising maps

Feature selection is an important and active issue in clustering and classification problems. By choosing an adequate feature subset, a dataset dimensionality reduction is allowed, thus contributing to decreasing the classification computational complexity, and to improving the classifier performance by avoiding redundant or irrelevant features. Although feature selection can be formally defined as an optimisation problem with only one objective, that is, the classification accuracy obtained by using the selected feature subset, in recent years, some multi-objective approaches to this problem have been proposed. These either select features that not only improve the classification accuracy, but also the generalisation capability in case of supervised classifiers, or counterbalance the bias toward lower or higher numbers of features that present some methods used to validate the clustering/classification in case of unsupervised classifiers. The main contribution of this paper is a multi-objective approach for feature selection and its application to an unsupervised clustering procedure based on Growing Hierarchical Self-Organising Maps (GHSOMs) that includes a new method for unit labelling and efficient determination of the winning unit. In the network anomaly detection problem here considered, this multi-objective approach makes it possible not only to differentiate between normal and anomalous traffic but also among different anomalies. The efficiency of our proposals has been evaluated by using the well-known DARPA/NSL-KDD datasets that contain extracted features and labelled attacks from around 2 million connections. The selected feature sets computed in our experiments provide detection rates up to 99.8% with normal traffic and up to 99.6% with anomalous traffic, as well as accuracy values up to 99.12%.

Capillary microreactors based on hierarchical SiO2 monoliths incorporating noble metal nanoparticles for the Preferential Oxidation of CO

Novel hierarchical SiO2 monolithic microreactors loaded with either Pd or Pt nanoparticles have been prepared in fused silica capillaries and tested in the Preferential Oxidation of CO (PrOx) reaction. Pd and Pt nanoparticles were prepared by the reduction by solvent method and the support used was a mesoporous SiO2 monolith prepared by a well-established sol–gel methodology. Comparison of the activity with an equivalent powder catalyst indicated that the microreactors show an enhanced catalytic behavior (both in terms of CO conversion and selectivity) due to the superior mass and heat transfer processes that take place inside the microchannel. TOF values at low CO conversions have been found to be ∼2.5 times higher in the microreactors than in the powder catalyst and the residence time seems to have a noticeable influence over the selectivity of the catalysts designed for this reaction. The Pd and Pt flexible microreactors developed in this work have proven to be effective for the CO oxidation reaction both in the presence and absence of H2, standing out as a very interesting and suitable option for the development of CO purification systems of small dimensions for portable and on-board applications.

Hierarchical indexing structure for efficient similarity search in video retrieval

With the rapid increase in both centralized video archives and distributed WWW video resources, content-based video retrieval is gaining its importance. To support such applications efficiently, content-based video indexing must be addressed. Typically, each video is represented by a sequence of frames. Due to the high dimensionality of frame representation and the large number of frames, video indexing introduces an additional degree of complexity. In this paper, we address the problem of content-based video indexing and propose an efficient solution, called the Ordered VA-File (OVA-File) based on the VA-file. OVA-File is a hierarchical structure and has two novel features: 1) partitioning the whole file into slices such that only a small number of slices are accessed and checked during k Nearest Neighbor (kNN) search and 2) efficient handling of insertions of new vectors into the OVA-File, such that the average distance between the new vectors and those approximations near that position is minimized. To facilitate a search, we present an efficient approximate kNN algorithm named Ordered VA-LOW (OVA-LOW) based on the proposed OVA-File. OVA-LOW first chooses possible OVA-Slices by ranking the distances between their corresponding centers and the query vector, and then visits all approximations in the selected OVA-Slices to work out approximate kNN. The number of possible OVA-Slices is controlled by a user-defined parameter delta. By adjusting delta, OVA-LOW provides a trade-off between the query cost and the result quality. Query by video clip consisting of multiple frames is also discussed. Extensive experimental studies using real video data sets were conducted and the results showed that our methods can yield a significant speed-up over an existing VA-file-based method and iDistance with high query result quality. Furthermore, by incorporating temporal correlation of video content, our methods achieved much more efficient performance.

Non-linear hierarchical visualisation

This thesis applies a hierarchical latent trait model system to a large quantity of data. The motivation for it was lack of viable approaches to analyse High Throughput Screening datasets which maybe include thousands of data points with high dimensions. High Throughput Screening (HTS) is an important tool in the pharmaceutical industry for discovering leads which can be optimised and further developed into candidate drugs. Since the development of new robotic technologies, the ability to test the activities of compounds has considerably increased in recent years. Traditional methods, looking at tables and graphical plots for analysing relationships between measured activities and the structure of compounds, have not been feasible when facing a large HTS dataset. Instead, data visualisation provides a method for analysing such large datasets, especially with high dimensions. So far, a few visualisation techniques for drug design have been developed, but most of them just cope with several properties of compounds at one time. We believe that a latent variable model (LTM) with a non-linear mapping from the latent space to the data space is a preferred choice for visualising a complex high-dimensional data set. As a type of latent variable model, the latent trait model can deal with either continuous data or discrete data, which makes it particularly useful in this domain. In addition, with the aid of differential geometry, we can imagine the distribution of data from magnification factor and curvature plots. Rather than obtaining the useful information just from a single plot, a hierarchical LTM arranges a set of LTMs and their corresponding plots in a tree structure. We model the whole data set with a LTM at the top level, which is broken down into clusters at deeper levels of t.he hierarchy. In this manner, the refined visualisation plots can be displayed in deeper levels and sub-clusters may be found. Hierarchy of LTMs is trained using expectation-maximisation (EM) algorithm to maximise its likelihood with respect to the data sample. Training proceeds interactively in a recursive fashion (top-down). The user subjectively identifies interesting regions on the visualisation plot that they would like to model in a greater detail. At each stage of hierarchical LTM construction, the EM algorithm alternates between the E- and M-step. Another problem that can occur when visualising a large data set is that there may be significant overlaps of data clusters. It is very difficult for the user to judge where centres of regions of interest should be put. We address this problem by employing the minimum message length technique, which can help the user to decide the optimal structure of the model. In this thesis we also demonstrate the applicability of the hierarchy of latent trait models in the field of document data mining.

Semisupervised learning of hierarchical latent trait models for data visualization

Recently, we have developed the hierarchical Generative Topographic Mapping (HGTM), an interactive method for visualization of large high-dimensional real-valued data sets. In this paper, we propose a more general visualization system by extending HGTM in three ways, which allows the user to visualize a wider range of data sets and better support the model development process. 1) We integrate HGTM with noise models from the exponential family of distributions. The basic building block is the Latent Trait Model (LTM). This enables us to visualize data of inherently discrete nature, e.g., collections of documents, in a hierarchical manner. 2) We give the user a choice of initializing the child plots of the current plot in either interactive, or automatic mode. In the interactive mode, the user selects "regions of interest," whereas in the automatic mode, an unsupervised minimum message length (MML)-inspired construction of a mixture of LTMs is employed. The unsupervised construction is particularly useful when high-level plots are covered with dense clusters of highly overlapping data projections, making it difficult to use the interactive mode. Such a situation often arises when visualizing large data sets. 3) We derive general formulas for magnification factors in latent trait models. Magnification factors are a useful tool to improve our understanding of the visualization plots, since they can highlight the boundaries between data clusters. We illustrate our approach on a toy example and evaluate it on three more complex real data sets. © 2005 IEEE.

Multicriteria Evaluation and Optimization of Hierarchical Systems

It is shown that any multicriteria problem can be represented by a hierarchical system. Separate properties of the object are evaluated at the lower level of the system, using a criteria vector, and a composition mechanism is used to evaluate the object as a whole at the upper level. The paper proposes a method to solve complex multicriteria problems of evaluation and optimization. It is based on nested scalar convolutions of vector- valued criteria and allows simple structural and parametrical synthesis of multicriteria hierarchical systems.

An Ontology- Content-based Filtering Method

Traditional content-based filtering methods usually utilize text extraction and classification techniques for building user profiles as well as for representations of contents, i.e. item profiles. These methods have some disadvantages e.g. mismatch between user profile terms and item profile terms, leading to low performance. Some of the disadvantages can be overcome by incorporating a common ontology which enables representing both the users' and the items' profiles with concepts taken from the same vocabulary. We propose a new content-based method for filtering and ranking the relevancy of items for users, which utilizes a hierarchical ontology. The method measures the similarity of the user's profile to the items' profiles, considering the existing of mutual concepts in the two profiles, as well as the existence of "related" concepts, according to their position in the ontology. The proposed filtering algorithm computes the similarity between the users' profiles and the items' profiles, and rank-orders the relevant items according to their relevancy to each user. The method is being implemented in ePaper, a personalized electronic newspaper project, utilizing a hierarchical ontology designed specifically for classification of News items. It can, however, be utilized in other domains and extended to other ontologies.